The 3¢-processing of viral DNA extremities is the first step in the integra-tion process catalysed by human immunodeficiency virus (HIV)-1 integrase (IN). This reaction is relatively inefficient and processed DNAs are usually detectedin vitro under conditions of excess enzyme. Despite such experi-mental conditions, steady-state Michaelis–Menten formalism is often applied to calculate characteristic equilibrium⁄kinetic constants of IN.